General Motors will be teaming up with the U.S. Navy to develop hydrogen-powered unmanned undersea vehicles (UUVs). Fuel-cell UUVs have the capacity to operate independently 70 days at a time, and would replace more limited battery-drive systems currently in use in so-called UUVs, according to Navy officials.

“If you want long endurance you really need fuel cells,” said Karen Swider-Lyons, head of the Alternative Energy Section at the Naval Research Laboratory.

In November, GM signed a multi-year contract with the U.S. Army to build and demonstrate an all-terrain vehicle powered by hydrogen fuel cells. The fuel cell reconnaissance vehicle is being built for the U.S. Army Tank Automotive Research, Development and Engineering Center. GM said that the demonstration will show the unique advantages its fuel cell technology can offer in an all-terrain tactical application.

The Navy has had UUVs in operation for year, but they’ve typically been about the size of a submarine’s torpedo. The military would like to make them larger with more features and functions and the ability to operate independently for longer periods of time.

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Fuel-cell “stacks” can be scaled up or down in size to fit into different sized vehicles, whether they operate on the road or under the water. The stack combines hydrogen gas with oxygen to create a stream of current that can operate an electric motor driving an automobile’s wheels, or an underwater vehicle’s propeller. They’re far more energy dense than batteries, and are known for being durable and flexible enough to provide power for both an underwater propulsion system and the electronic systems crammed into a UUV.

“Our in-water experiments with an integrated prototype show that fuel cells can be game changers for autonomous underwater systems,” said Frank Herr, department head for the Navy’s Ocean Battlespace Sensing research unit, in a statement.

While Hyundai, Toyota, and Honda are committed to bringing fuel-cell technology to passenger vehicles, GM continues to lag behind. GM has been testing hydrogen technology in a fleet of prototypes like this Chevy Equinox, and plans to bring out a fuel-cell vehicle by the end of decade.

The UUVs are still in the prototype phase, and it’s not yet clear when GM’s fuel cell system will be going out to sea. The fuel-cell technology is actually ready to go, Swider-Lyons said. Developing the necessary autonomous control systems is the more serious technical challenge.

The Detroit Bureau